Previous sharpeners disclosed in U.S. Pat. Nos. 5,611,726, 4,627,194, 4,897,965 and 5,005,319 describe a variety of sharpeners for knives and related tools and products where sharp edges are required.
U.S. Pat. No. 5,611,726 (marketed as a commercial sharpener) describes a two stage high speed sharpener particularly designed for applications where the user wants an extremely sharp edge with a measurable amount of "bite" on the resulting knife edge. This type of edge is particularly desired by commercial users.